1. Field of the Invention
This invention relates to a method for introducing a prestress using a hollow prestressed steel rod for applying a prestress to a concrete member by means of pretensioning.
2. Description of the Prior Art
In the prior art, there are a pretensioning and a posttensioning in the methods for introducing a prestress into a precast concrete member (PC member) in which a prestressed steel is used.
The pretensioning is a main producing mode in which the pretensioning is carried out by a long-line process in a professional factory, and there is a disadvantage in that the pretensioning requires a strong abutment and a jack having a large capacity.
In the case of using the posttensioning, a fixture is necessary and generally both a sheath and grout are also required. The cost of the product becomes higher in comparison with that of pretensioning.